Corps cuts lake flows to the coastal estuaries

Debbie Akins

7 months ago

Florida Gov. Rick Scott wants to send excess freshwater from Lake Okeechobee south, but existing water conveyance structures, direct rainfall south of the lake, the Tamiami Trail and the Department of the Interior make that difficult, if not impossible.

Heavy rain in May — some areas received more than 400 percent of average rainfall — left all of South Florida saturated with freshwater. As runoff from the Kissimmee River basin flowed south into Lake Okeechobee, the lake level quickly rose. The U.S. Army Corps of Engineers tries to keep the lake on schedule between 12.5 and 15.5 feet above sea level. Higher levels damage the lake’s ecology by drowning the marshes along its shores. These marshes are critical habitat for fish and wildlife and also help clean the water. Higher levels also threaten the stability of the earthen Herbert Hoover Dike.

During hurricane season, the corps tries to leave enough capacity in Lake Okeechobee to anticipate the heavy flows from storms, which can cause the lake to rise as much as 4 feet in a few weeks.

Col. Jason Kirk, Jacksonville District commander, visited the Herbert Hoover Dike on June 21 to assure those living south of the dike that work is continuing to keep them safe and to announce a reduction in lake releases toward the northern estuaries east and west.

On June 1, the corps started flowing up to 1,800 cubic feet per second (cfs) east to the St. Lucie from the lake as measured at the St. Lucie Lock, and up to 4,000 cfs west to the Caloosahatchee at the Moore Haven Lock.

Flow south of the lake is currently limited by the capacity of the canals and by the Tamiami Trail, which acts as a dam bisecting the Everglades from Tampa to Miami. The Comprehensive Everglades Restoration Plan (CERP) calls for raising part of the roadway. The corps recommended 11 miles of raised bridging. Currently only 1 mile of raised bridging has been completed; another 2.6 miles is under construction.

An additional barrier to flow south is the Department of the Interior, which has blocked flow under the Tamiami Trail to protect the nesting area of the Cape Sable sea sparrow. To protect the nesting grounds, two of the S-12 gates (which would allow flow under the trail) are closed. On June 20, flow under the trail was 1,316 cfs — about 700 million gallons per day. If all of the S-12 gates were open, that flow could nearly double. This would still only be a fraction of the water that has been flowing east and west since June 1.

Flow south is also limited by restrictions on phosphorus levels. While the Lake Okeechobee inflows from the north average around 140 parts per billion of phosphorus, water entering Everglades National Park must be no more than 10 ppb. So the water that flows through the lake must be sent through Stormwater Treatment Areas (STAs) to be cleaned before it can be sent south into the Everlgades.

Due to heavy rainfall in May, those STAs were at or above capacity when the releases east and west started June 1.

On June 20, water from the lake was flowing south at 1,031 cfs to the STAs, then into the Water Conservation Areas. Clean water from the WCAs was flowing at a rate of 1,316 cfs to Everglades National Park.

Col. Jason Kirk of the U.S. Army Corps of Engineers Jacksonville District visited the Herbert Hoover Dike between Clewiston and South Bay on June 21 to assure residents that rehabilitation work on the dike is continuing. At left is Mali Gardner, mayor of Clewiston. At right is Janet Taylor of Guardians of the Glades.

On Wednesday, June 20, Gov. Scott directed Florida Department of Environmental Protection Secretary Noah Valenstein to issue an order urging the U.S. Army Corps of Engineers and the South Florida Water Management District (SFWMD) to take emergency actions to help redirect the flow of water out of Lake Okeechobee to the south. This order is in response to the Army Corps decision to release water from Lake Okeechobee west to the Caloosahatchee River and east to the St. Lucie River estuaries and the Indian River Lagoon. Since the corps began releasing water from Lake Okeechobee this year, DEP has continued to respond to reports of algal blooms in both rivers, as well as continued reports on Lake Okeechobee.

Gov. Scott said: “In previous years, we have seen algae blooms develop in our waterways due to the federal water discharges from Lake Okeechobee. The U.S. Army Corps of Engineers directs these discharges when the dike is nearing capacity and at risk of breaching. Unfortunately, the federal government has had decades to fix the dike that they operate, but have failed to do so. In response, I have put up state funding to fix the federal dike and I have secured an agreement from the Trump administration to expedite the repairs. Also, working with the Florida Legislature, I signed a law that accelerated the EAA reservoir to move more water south of the lake, to help ease these discharges. But, while we continue to wait on the federal government’s action on the dike and EAA reservoir, we are going to do all we can to protect our waterways as we enter the hot summer months in Florida.

“I am directing DEP Secretary Noah Valenstein to issue a Secretarial Emergency Order urging the Army Corps and SFWMD to take emergency actions to lower lake levels and help redirect the flow of water out of Lake Okeechobee to the south. Two years ago, we saw the devastating impact of releases from Lake Okeechobee into the St. Lucie and Caloosahatchee rivers and estuaries, which caused widespread algal blooms and led to the declaration of a state of emergency in four counties. We are taking immediate action to do everything in our power to solve this problem.

“With this order, and the cooperation of the Army Corps and other federal agencies, the state will continue to work to mitigate and minimize the impacts of algal blooms we witnessed in the past. We will continue to fight to secure federal action and urge the federal government to authorize the EAA reservoir and fully fund the Herbert Hoover Dike repairs.”

DEP Secretary Valenstein said: “We want to take every step possible to allow the Army Corps and water management district to proactively address high water levels and move more water south and away from our communities. While lake releases will continue to depend on the Army Corps’ water operations, the state is committed to providing flexibility to the Army Corps, while also standing alongside Floridians.”

Prior to the Army Corps’ releases, the SFWMD was already maximizing opportunities to lower water levels in all three water conservation areas south of the lake, and this emergency order will provide additional opportunities to move clean water out of the water conservations areas to the south. SFWMD continues to make use of all available water storage, including recently completed components of Gov. Scott’s Restoration Strategies Plan, such as the A-1 and L-8 Flow Equalization Basins.

On Thursday, the corps announced that it will slightly reduce the flows east and west starting Friday, June 22.

Starting Friday (June 22), the target flow for the Caloosahatchee Estuary will be reduced to 3,000 cfs as measured at W.P. Franklin Lock & Dam (S-79) located near Fort Myers. The target flow for the St. Lucie Estuary will be reduced to a seven-day average of 1,170 cfs as measured at St. Lucie Lock & Dam (S-80) near Stuart.

Because these releases will include local flow, the actual flow from the lake will be less than the target flow number. For example, on June 20, 1,760 cfs was flowing into the Caloosahatchee from local basin runoff. With the new schedule, that would have meant only 1,240 cfs could have been released at Moore Haven.

“The discharges over the past three weeks have stopped the rise in the lake,” said Col. Jason Kirk, Jacksonville District commander. “Inflows have also slowed since late May. Based on current conditions, the guidance under the Lake Okeechobee Regulation Schedule calls for reduced flows.”

The corps will release water to the St. Lucie Estuary from the lake in a “pulse” fashion, which means flows will vary during the seven-day release period. Additional runoff from rain in the Caloosahatchee and St. Lucie basins could also occasionally result in flows that exceed targets.

“The pulse releases will be set up to include two consecutive days of no flow for the St. Lucie Estuary,” said Col. Kirk. “This should allow some tidal flushing, which will help aquatic life in the estuary.”

The corps is working with state officials to determine what other actions can be taken to address water management challenges in South Florida.

Col. Kirk said while they appreciate the need to protect the estuaries, the governor’s order does not change the way the corps follows the existing Lake Okeechobee Regulation Schedule (LORS).

“In collaboration with the South Florida Water Management District and in consultation with our regional headquarters and federal resource agencies, we constantly seek to identify and implement the optimal solutions in a system with limited options,” said Col. Kirk. “Our close federal-state partnership serves us well in day-to-day operations as it does in our shared pursuit of Everglades restoration wherein we’re working to implement long-term improvements to South Florida’s water quantity, quality, timing and distribution.”